An MVA (multi-domain vertical alignment) mode liquid crystal display device has a wider viewing angle characteristic than a TN mode liquid crystal display device, and therefore, is currently used extensively in various liquid crystal display devices including TV monitors (see Patent Documents Nos. 1 and 2, for example).
In an MVA mode liquid crystal display device, a domain control structure (which is also called an “alignment control structure”) is provided for each of the two substrates thereof, which face each other with a vertical alignment liquid crystal layer interposed between them, so as to face the liquid crystal layer, thereby producing multiple liquid crystal domains in which directors have multiple different alignment directions (i.e., tilt directions). As such a domain control structure, either an opening (e.g., a slit) that has been cut through an electrode or a dielectric projection (e.g., a rib) that has been formed on an electrode to face the liquid crystal layer is used.
Typically, domain control structures, which run straight in two directions that intersect with each other at right angles, are arranged on each of the two substrates. And the domain control structures provided for one and the other of the two substrates are arranged so as to run alternately and parallel to each other when viewed perpendicularly to the substrates. As a result, when a voltage is applied to the liquid crystal layer of an arbitrary pixel, four domains, in which liquid crystal molecules tilt in four different directions (which will be sometimes referred to herein as “liquid crystal domain director directions”), are produced between those linear domain control means so that the tilt direction of the liquid crystal molecules in any one of those four domains defines an angle of about 90 degrees with respect to that of the liquid crystal molecules in an adjacent domain thereof. In a typical arrangement, four liquid crystal domains, in which the liquid crystal domain directors define an azimuth angle of 45 degrees with respect to the polarization axes (i.e., transmission axes) of two polarizers that are arranged as crossed Nicols, are formed. If an azimuth angle of zero degrees is supposed to be defined by the polarization axis direction of the one of the two polarizers (e.g., the horizontal direction on the display screen) and if the counterclockwise direction is supposed to be the positive direction, then the directors in those four liquid crystal domains will have azimuth angles of 45, 135, 225 and 315 degrees, respectively.
In this description, the “pixel” refers to the smallest unit of display to be conducted by the liquid crystal display device. In the case of a color display device, the “pixel” refers to the smallest unit for representing each of its primary colors, and is sometimes called a “dot”. In a typical color display device, one color display pixel is formed by three pixels that represent the colors red, green and blue that are the three primary colors of light. And by controlling the luminances of those pixels, the color display device conducts a display operation in colors.
Thus, to reduce the viewing angle dependence of the γ characteristic of an MVA mode liquid crystal display device, the applicant of the present application lately disclosed, in Patent Document No. 3, a liquid crystal display device that can reduce the viewing angle dependence of the γ characteristic by dividing a single pixel into a number of subpixels with mutually different brightness values, and a method for driving such a device. In particular, such a device can reduce the viewing angle dependence of the γ characteristic that manifests itself as a phenomenon that the display luminances at low grayscales become higher than a predetermined luminance (i.e., the image on the screen looks generally whitish) in a normally black mode display operation. Such a display or drive mode will sometimes be referred to herein as “area-grayscale display”, “area-grayscale drive”, “multi-pixel display” or “multi-pixel drive”.
Recently, a method in which an increased number of primary colors are used to conduct a display operation in order to broaden the range in which a liquid crystal display device can represent colors (which is called a “color reproduction range”) has been proposed. For example, a liquid crystal display device with color display pixels, each of which includes not only red (R), green (G) and blue (B) pixels but also a pixel in at least one more color (e.g., a yellow (Y), cyan (C), magenta (M) or white (W) pixel), has been disclosed. When a white pixel is added, the color reproduction range cannot be broadened but the display luminance can be increased.
The entire disclosures of Patent Documents Nos. 1 to 3 are hereby incorporated by reference.